Weight Loss at a Cost: Implications of High-Protein, Low-Carbohydrate Diets
Gabel, Kathe A., Lund, Robin J., JOPERD--The Journal of Physical Education, Recreation & Dance
Promoters of high-protein, low-carbohydrate (HPLC) diets claim that they can guarantee quick weight loss. Introduced by Robert Atkins in 1972, this type of diet achieved considerable popularity at first, but its popularity soon declined as people failed to attain the advertised weight loss. Today, however, this diet has regained attention among people who wish to shed extra pounds. Among the books touting HPLC diets are Dr. Atkins' New Diet Revolution (Atkins, 1999), The Zone (Sears, 1995), and Sugar Busters (Steward, Bethea, & Andrews, 1998). Readers have made these books very popular. For example, Atkins (2001) on his web site indicates that his book "was the top-selling diet/health book in America in 1997 and 1998."
The average American is not alone in being drawn to this extraordinary prescription for weight loss. Athletes, young and old, are also easily enticed by the claims of quick weight loss and greater athletic success. Coaches and health and fitness professionals there-fore need to examine these claims in the light of scientific evidence in order to better discharge their duty to their athletes and students. To that end, this article will address the claims of HPLC diets by examining relevant scientific reports. Possible adverse effects will also be addressed.
Claim 1: Weight loss is attributed to the composition of the diet (i.e., high protein, low carbohydrate).
Scientific Reports. The only healthful way to lose weight is to achieve a negative energy balance. To accomplish this, three methods are possible. If one maintains his or her usual energy output, while decreasing the amount of energy consumed as food, a negative energy balance will result. High-protein, low-carbohydrate diets are typically low-calorie, thereby causing a negative energy balance, hence weight loss (Boucher, 1999). The second way to accomplish a negative energy balance is to maintain the usual food intake, while increasing energy output by exercise. The third and most effective method combines the first two. By creating a negative energy balance through a combination of diet and exercise, lean muscle mass can be retained while body fat is decreased.
The fact that the hypocaloric HPLC diet promotes weight loss is not disputed. The question is what role the diet's composition plays. Dr. Atkins recommends that dieters consume 1,400 calories per day during the first two weeks of the diet (Boucher, 1999). For a moderately active 18-year-old female who weighs 125 pounds, this is only 60 percent of her recommended level of energy intake (Food and Nutrition Board, 1989). In other words, the diet achieves its results by severely reducing caloric intake. This has nothing to do with the diet's composition. A hypocaloric diet of any composition will produce weight loss. It is negative energy balance, rather than diet composition, that is responsible for weight loss.
Claim 2: Insulin promotes the storage of fat; therefore by limiting carbohydrate, dieters will decrease levels of insulin and body fat.
Scientific Reports. Insulin is an anabolic hormone released during the fed state that allows for the uptake of glucose into cells and promotes the synthesis of glycogen and fat. High levels of insulin in the blood are associated with obesity (Bagdade, Bierman, & Porte, 1967). Because of insulin's effect on fat synthesis, promoters of HPLC have targeted insulin as the "bad guy." However, insulin does not cause obesity; indeed, the opposite is true. Obesity causes high levels of insulin to accumulate (Almazov, Blagosklonnaia, Shliakhto, & Krasil'nikova, 1999; Hashimoto & Saito, 2000). Simply stated, obesity decreases the ability of the liver to clear insulin, resulting in increased levels of insulin (Bergman, et al., 2001).
To assess the effect of carbohydrate levels on weight loss, Golay, Allaz et al. (1996) and Golay, Eigenheer et al. (1996) fed subjects hypocaloric diets that consisted of 15, 25 or 45 percent of calories as carbohydrate. …